Ultrastretchable, Highly Transparent, Self-Adhesive, and 3D-Printable Ionic Hydrogels for Multimode Tactical Sensing

Ionic gel-based electronic devices are essential in future healthcare/biomedical applications, such as advanced diagnostics, therapeutics, physiotherapy, etc. However, considerable efforts have been devoted to integrating ultrahigh stretchability, transparency, self-adhesion, and a low-cost manufacturing process in one material for dealing with a variety of application scenarios in the real world. Here, we describe an ionically conductive hydrogel-based electronic technology by introducing charge-rich polyzwitterions into a natural polysaccharide network. The proposed hydrogel possesses ultrahigh stretchability (975%), unique optical transmittance (96.2%), and universal conformal adhesion. The bionic hydrogel electronic devices possess superior dual force/temperature sensation with high sensitivity. Moreover, we develop dedicated sensor arrays via an additive manufacturing route and demonstrate the feasibility of monitoring physical activity or analyzing the mental state of a human body based on the multichannel signal acquisition of joint bending, pulse, vocal-cord vibration, electroencephalogram, eye movement, body temperature, etc. This all-in-one strategy based on a versatile ionic hydrogel electronic platform is anticipated to open up new tactical sensing applications in smart robotics, human–machine interfaces, and wearable monitoring systems.